{"id":"AZL-69554","summary":"CVE-2025-37786 affecting package kernel 5.15.200.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: dsa: free routing table on probe failure\n\nIf complete = true in dsa_tree_setup(), it means that we are the last\nswitch of the tree which is successfully probing, and we should be\nsetting up all switches from our probe path.\n\nAfter \"complete\" becomes true, dsa_tree_setup_cpu_ports() or any\nsubsequent function may fail. If that happens, the entire tree setup is\nin limbo: the first N-1 switches have successfully finished probing\n(doing nothing but having allocated persistent memory in the tree's\ndst-\u003eports, and maybe dst-\u003ertable), and switch N failed to probe, ending\nthe tree setup process before anything is tangible from the user's PoV.\n\nIf switch N fails to probe, its memory (ports) will be freed and removed\nfrom dst-\u003eports. However, the dst-\u003ertable elements pointing to its ports,\nas created by dsa_link_touch(), will remain there, and will lead to\nuse-after-free if dereferenced.\n\nIf dsa_tree_setup_switches() returns -EPROBE_DEFER, which is entirely\npossible because that is where ds-\u003eops-\u003esetup() is, we get a kasan\nreport like this:\n\n==================================================================\nBUG: KASAN: slab-use-after-free in mv88e6xxx_setup_upstream_port+0x240/0x568\nRead of size 8 at addr ffff000004f56020 by task kworker/u8:3/42\n\nCall trace:\n __asan_report_load8_noabort+0x20/0x30\n mv88e6xxx_setup_upstream_port+0x240/0x568\n mv88e6xxx_setup+0xebc/0x1eb0\n dsa_register_switch+0x1af4/0x2ae0\n mv88e6xxx_register_switch+0x1b8/0x2a8\n mv88e6xxx_probe+0xc4c/0xf60\n mdio_probe+0x78/0xb8\n really_probe+0x2b8/0x5a8\n __driver_probe_device+0x164/0x298\n driver_probe_device+0x78/0x258\n __device_attach_driver+0x274/0x350\n\nAllocated by task 42:\n __kasan_kmalloc+0x84/0xa0\n __kmalloc_cache_noprof+0x298/0x490\n dsa_switch_touch_ports+0x174/0x3d8\n dsa_register_switch+0x800/0x2ae0\n mv88e6xxx_register_switch+0x1b8/0x2a8\n mv88e6xxx_probe+0xc4c/0xf60\n mdio_probe+0x78/0xb8\n really_probe+0x2b8/0x5a8\n __driver_probe_device+0x164/0x298\n driver_probe_device+0x78/0x258\n __device_attach_driver+0x274/0x350\n\nFreed by task 42:\n __kasan_slab_free+0x48/0x68\n kfree+0x138/0x418\n dsa_register_switch+0x2694/0x2ae0\n mv88e6xxx_register_switch+0x1b8/0x2a8\n mv88e6xxx_probe+0xc4c/0xf60\n mdio_probe+0x78/0xb8\n really_probe+0x2b8/0x5a8\n __driver_probe_device+0x164/0x298\n driver_probe_device+0x78/0x258\n __device_attach_driver+0x274/0x350\n\nThe simplest way to fix the bug is to delete the routing table in its\nentirety. dsa_tree_setup_routing_table() has no problem in regenerating\nit even if we deleted links between ports other than those of switch N,\nbecause dsa_link_touch() first checks whether the port pair already\nexists in dst-\u003ertable, allocating if not.\n\nThe deletion of the routing table in its entirety already exists in\ndsa_tree_teardown(), so refactor that into a function that can also be\ncalled from the tree setup error path.\n\nIn my analysis of the commit to blame, it is the one which added\ndsa_link elements to dst-\u003ertable. Prior to that, each switch had its own\nds-\u003ertable which is freed when the switch fails to probe. But the tree\nis potentially persistent memory.","modified":"2026-04-01T05:21:35.617805Z","published":"2025-05-01T14:15:42Z","upstream":["CVE-2025-37786"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-37786"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:2","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"5.15.200.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-69554.json"}}],"schema_version":"1.7.5"}